9: Muscles and Muscles Tissue Objectives 1. Compare and contrast the basic types of muscle tissue and describe four special characteristics of muscle tissue. 2. List four important functions of muscle tissue. 3. Describe the gross structure of a skeletal muscle, including its coverings. 4. Describe the microscopic structure and functional roles of the myofibrils, sarcoplasmic reticulum, and T tubule(s) of skeletal muscle fibers. 5. Describe the sliding filament model of muscle contractions. 6. Explain how muscle fibers are stimulated to contract by describing events that occur at the neuromuscular junction. 7. Describe how an action potential is generated. 8. Follow the events of excitation-contraction coupling that lead to cross bridge activity. 9. Define motor unit and muscle twitch and describe the events occurring during the three phases of a muscle twitch. 10. Define muscle tone. 11. Differentiate between isometric and isotonic contractions and concentric and eccentric contractions. 12. Describe three ways in which ATP is regenerated during skeletal muscle contraction. 13. Define oxygen deficit and muscle fatigue. List possible causes of muscle fatigue. 14. Distinguish among the three types of skeletal muscle fibers. If it's bold, it's particularly gold! I. Overview of Muscle Tissues (pp. 276–277; Table 9.3) A. Types of Muscle Tissue 1. Skeletal muscle is associated with the bony skeleton, and consists of large cells that bear striations and are controlled voluntarily . 2. Cardiac muscle occurs only in the heart, and consists of small cells that are striated and under involuntary control. 3. Smooth muscle is found in the walls of hollow organs [ visceral ], and consists of small, elongated cells that are not striated and are under involuntary control. B. Special Characteristics of Muscle Tissue 1. Excitability , or irritability, is the ability to receive and respond to a stimulus. 2. Contractility is the ability to contract forcibly when stimulated. 3. Extensibility is the ability to be stretched. 4. Elasticity is the ability to resume the cells’ original length once stretched. C. Muscle Functions 1. Muscles produce movement by acting on the bones of the skeleton, pumping blood, or propelling substances throughout hollow organ systems. 2. Muscles aid in maintaining posture by adjusting the position of the body with respect to

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